Recovery of phenolics from sour cherry pomace (Prunus cerasus L.) by ultra- and nanofiltration

The production of sour cherry wine generates large amounts of pomace that is mainly composed by the stones, stems and skins of the pressed berries, as well as yeast cells and fermentation byproducts. Even though it is normally regarded as waste, sour cherry pomace is very rich in nutrients, pigments and bioactive compounds. Aqueous buffer extraction followed by purification via membrane technology is a sustainable approach for the recovery of value‐added products from the pomace, such as anthocyanins and phenolic acids that can be used in the food, cosmetic and pharmaceutical industries. In the present work, pomace from the Danish sour cherry wine producer Frederiksdal Kirsebærvin was extracted in a pH 3 citrate‐phosphate buffer. The extraction slurry was
filtered through a 5 mm sieve to remove the stones and stems. The remaining suspension of cherry skins was filtered through an ultrafiltration (UF) ceramic membrane (ϒ‐Al2O3, 20 kDa, Inopor), which separated the cell debris and yeast from the extract. The UF permeate was subjected to nanofiltration (NF) (polyamide‐TFC, ~150‐300 Da, GE Osmonics) in order to retain anthocyanins and
phenolic acids, while permeating ethanol, glycerol and other small impurities. The flux during UF at a transmembrane pressure (TMP) of 0.7 bar stabilized around 25 LMH, whereas the NF permeate flux at a TMP of 10 bar experienced a continuous decay from 30 to 3 LMH during operation (VCR 3.6). In both UF and NF the pure water flux was fully recovered after cleaning the membranes.


Acknowledgements
This project has received funding from the European Regional Development Fund as part of the Interreg North Sea Region project project 38-2-4-17 BIOCAS , circular BIOmass CAScade to 100%.